Coilable tape measures are widely employed to facilitate measurement and to effect the return of an extended tape blade into a housing for storage and carrying purposes. The tape blade is constructed of metal, and an element is secured to its outer surface end, which is referred to as a hook. The hook aids in the use of the tape blade. The hook is a bent metal strip secured to the tape blade by rivets. The tape blade is spring-loaded to be biased toward a retracted position within the housing. When the tape blade is completely retracted and coiled within the housing, the hook remains outside the housing. There is a positive locking mechanism that allows the tape blade to be locked in place when the tape blade is extended for convenience in making measurements. The locking mechanism usually operates on the tape blade within the housing and an actuator, e.g., a push button, is located on a peripheral surface so that it can be easily manipulated by the thumb as the tape measurer is grasped by the user. The actuator can be pressed on or off by the user. Usually the lock is actuated when the tape blade is extended and correctly positioned within a given extended position and the lock is released when the user desires the tape blade to be automatically retracted and coiled within the housing.
A spring used to retract and coil the extended tape blade into the housing is quite powerful, particularly with respect to a tape blade extending a large distance from the housing. There is a tendency for the extended length of tape blade to flex or whip as it is being withdrawn into the housing as an aperture into the housing provides an effective pivot point. The hook can also provide a second point of pivoting or flexure for the extended tape with the metal tape bending about the inner end of the hook. This whipping and flexing of the hook as the tape blade is being retracted can cause fatigue at the inner end of the tape blade and the hook.
The retraction and coiling of the tape blade into the housing is stopped rather abruptly by the abutment of the hook against the wall of the housing about the aperture. There is a tendency for shock loading about the rivets or other means for fastening the hook to the tape blade to produce fatigue or shear. Thus, it is quite common for the tape blade to fracture or shear in the area of the hook, which, in turn, causes the tape blade to be retracted and coiled completely into the housing, thereby preventing further use of the measuring tape. In addition, if the tape blade is extended a large distance from the housing and is then retracted into the housing, the whipping or flexing of the hook can mar the surface of a work piece.
It is an object of the present inventions to provide a measuring tape with a decelerating mechanism that is used to control the speed at which an extended tape blade is retracted into a housing chamber and coiled.
It is also an object of the present invention to provide a measuring tape with a decelerating mechanism that is used to prevent fatigue, rupture, shear, or fracture to the outer end of the tape blade and hook on the tape blade upon retraction of an extended tape blade into the housing.
Another object of the present invention is to provide a decelerating mechanism that fits easily into the measuring tape housing.
It is a further object of the present invention to provide a decelerating mechanism that allows an extended tape blade to be stopped temporarily while being retracted into the housing through the aperture.
It is an even further object of the present invention to provide a decelerating mechanism and locking mechanism on two peripheral surfaces of the measuring tape.
Still yet another object of the present invention is to provide a decelerating mechanism on the bottom peripheral surface of the measuring tape for convenient griping and use by the user's fingers while an extended tape blade is being retracted and coiled into the housing through the aperture.
Still yet an even further object of the present invention is that the decelerating mechanism be large enough to accommodate a few fingers.
A still further object of the present invention is to provide a decelerating mechanism having no engagement with the tape blade when not in use.
A still yet even further object of the present invention is to provide a decelerating mechanism that does not destroy or scrape-off any of the graduation lines on the tape blade.
A still yet even further object of the present invention is to provide a decelerating mechanism that is easy to assemble within the tape measure.